Honing machine



, March 7, 1944. H. CALDWELL ETAL HONING MACHINE Filed Aug. l, 1941 3Sheets-Sheet 2 .J L y wi w wav@ @Mem ,n w El! NU M T H W///Q/ N wm @QM Md FJ L Q//W/ w March 7; 1944. H. J. CALDWELL x-:TAL

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Patented Mar. 7, 1944 HONING MACHINE Harry J. Caldwell and Earnest Y.Seborg, Rockford, Ill., assignors to Barnes Drill Co., Rockford, Ill., acorporation of Illinois Application August 1, 1941, Serial No. 404,962

17 Claims.

The invention relates to honing machines generally and more particularlyto improved power actuated means for expanding the honing tools used insuch machines.

One object of the invention is to provide an improved tool expandingmechanism operative to eiTect a rapid initial expansion of a honing toolto operatively associate the abrasive element thereof with the Work andthereafter to effect a positive and progressive expansion of the tool inintermittent steps while the abrasive elements are operating on thework.

Another object is to provide novel means for electing expansion of ahoning tool with either a uniform or a progressively increasing.pressure in accordance with the resistance offered to the shifting ofthe tool adjusting member.

Still another object is to provide improved means for effecting positivestepped expansion of the honing tool during the working cycle of themachine and rapid contraction of the tool at the end of the cycle or atany point in the cycle at which the machine may be stopped.

It is also an object of the invention to provide novel safety mechanismoperative tov limit the expanding pressure on the hone and therebyprevent damage to the tool or work.

Other objects and advantages of the invention will become apparent fromthe following detailed description of the preferred embodimentillustrated in the accompanying drawings in which:

Figure 1 is a vertical sectional view of the tool spindle supportinghead of a honing machine embodying the features of the invention.

Fig. 2 is a horizontal sectional view of the spindle head taken alongthe line 2-2 of Fig. l.

Fig. 3 is a horizontal sectional view of the spindle head taken alongthe line 3--3 of Fig. l.

Fig. 4 is a diagrammatic View showing the electrical and hydrauliccircuits and their rela-- tionship to the operating and control elementsof the machines.

For purposes of illustration the invention has been shown and will bedescribed herein as embodied in a single spindle internal honing machineof the type in which the relative ro-tational and reciprocatorymovements of the too-l and Work are eiected by rotating andsimultaneously reciprocating the tool while the work is held stationary.It is to be understood, however, that the invention is not limited tohoning machines of this particular type but is readily applicable toother types of honing machines as well as to other of machine tools. Itis also to be understood that various modifications and adaptations maybe made in the form, construction and arrangement of the parts withoutdeparting from the spirit and scope of the invention as expressed in theappended claims.

Referring now to Figs. 1 and 4 of the drawings, the machine selected toillustrate the invention comprises generally an upright frame or columnIB (Fig. 1) on the face of which are mounted a pair of spacedcylindrical guide bars H forming a vertical guideway for a reciprocatoryhead constituting, in this instance, a support for a conventional honingtool I3 (Fig. 4). The tool is carried in the usual manner by a tubulartool spindle I4 suitably journaled on the head l2. The work to beoperated on by the tool such as workpiece W is stationarily supported ona suitable work support or table l5.

In order to obtain the relative rotational and reciprocatory movementsof the tool and work required for the performance of the honingoperation, suitable power driven means is provided for rotatably drivingthe spindle and for simultaneously reciprocating the head l2 whichcarries the spindle. As herein shown, the spindle is driven by anelectric motor M (Fig. 4) through the medium of a splined drive shaft2li and gears 2l, and 23. These gears are rotatably supported on thehead and are reciprocable therewith. The gear 2i has a splined drivingconnection with the shaft 2!) while the gear 23 is keyed or otherwisefixed to the spindle I4 Within the head l2.

The means for reciprocating the head I2 comprises, in this instance, apressure iiuid actuator herein shown as a piston 25 (Fig. 4) Working ina vertical cylinder 26 suitably attached to the machine frame. A pistonrod 2'! connects the piston with the head. Pressure fluid is supplied tothe cylinder 2-5 by a pump P driven by an electric motor MI. Aconventional pressure fluid actuated reversing valve RV operated undercontrol of a pilot valve PV connects the respective ends of the cylinderlto the pump and to a drain 28 alternately to effect the reciprocationof the piston, The pilot valve is actuated in well known manner byashiftable control rod 29 having spaced limit stops 3G and 3l and anintermediate stop 32 engageable by a dog or other suitable member 33carried by the head l2 and reciprocable therewith. A pressure reliefvalve VI limits the pressure in the fluid supply circuit to a safevalue.

The conventional honing tool employed for honing internal cylindricalsurfaces, of which the tool I3 is an example, comprises a series ofabrasive elements or honing stones 35 (Fig. 4) arranged around theperiphery of a cylindrical carrier 3S for movement radially thereof.'I'he abrasive elements are normally held in their inner or contractedposition by suitable springs and are shifted outwardly or expanded bymeans of an adjusting rod 31 (Figs. 1 and 4) extending axially throughthe hollow shank of the tool and through the tubular spindle I4 on whichthe tool is carried.

In the operation of the machine the tool is inserted in the work withthe abrasive elements contracted. It is then expanded, that is, theabrasive elements are shifted radially outwardly into operativeengagement with the surface to be operated on. The expanding effort mustbe continued of course while the elements perform their metal removingfunctions. For some types of work it has been found that greatereiiiciency is attained if the expanding pressure is progressivelyincreased in relatively small, graduated steps as the honing operationproceeds. The invention provides novel power actuated mecha nism foreffecting such stepped expansion of the honing tool during the workingportion of the cycle and for reducing the non-working portion of thecycle to a minimum by providing rapid initial expansion and rapidcontraction of the tool to bring the abrasive elements into engagementwith the surface of the work and to return them to their inner positionsto condition the tool for withdrawal from the work. Moreover the steppedexpansion of the honing tool is effected in a positive manner withoutinterfering and V3 control the delivery of pressure iiuid to therespective actuators as will appear present ly. The pressure in thesupply circuit is maintained at the desired level and the building up ofexcessive pressure in the system is prevented by a conventional reliefvalve V4. A pressure regulating valve V5 of any suitable type may beinterposed in the branch line leading to the actuator 4I to permitindependent regulation of the pressure of the iiuid supplied thereto.

`In the particular embodiment illustrated, the

actuators are arranged to operate through an elongated tubular actuatingmember 42 to impart endwise movements to the tool adjusting rod 31 bothto effect rapid initial expansion and progressive stepped expansion ofthe honing tool.` The actuating member 42 as herein shown is arrangedabove and axially alined with the tool adjusting rod 31. At its lowerend the memberis operatively connected to the adjusting rod 'so thatendwise movements of the member are trans' ferred to the rod. y

The operative connection between the mem ber 42 and the rod 31 isprovided in the present instance by a yieldable safety release mechanismwhich efectually prevents the application of excessive pressure to theabrasive elements of the tool and thus protects the elements and thework from damage under abnormal working con-- ditions. Asl shown in Fig.1, the mechanism in its preferred form comprises a headed connectingelement 43 having a cylindrical shank 44 of reduced diameter slidablyfitted in a chamber 45 formed by a counter bore in the lower end of thetubular member 42. A pin 45 extending transversely through the shank ofthe element and engaging in oppositely disposed longitudinal slots 41 inthe member acts to hold the parts in assembled relation and to permitlimited relative movement therebetween longitudinally of the member. Theconnecting member is yieldably urged outwardly with respect to thetubular member by suitable resilient means such as a spring 48interposed between the end of the shank 44 and the adjacent end of anadjusting bar 49 disposed within the tubular member with its lower endprojecting into the chamber 45. A screw plug 50 threaded into the upperend of the member 42 provides for adjusting the position of the bar 49and thus for regulating the tension of the spring 48. A second plug 5Imay be screwed into the end of the member 42 to lock they firstmentioned plug and bar in adjusted position.

The connecting element 43 serves to transmit the endwise movements ofthe member 42 to the tool adjusting rod 31 with which it is operativelyconnected. This connection as herein shown is provided by anantifriction thrust bearing 52 carried in a recess in the enlarged endportion of a sleeve member 53 iixed to the upper end of the tooladjusting rod. The bearing thus permits relative rotation of the partsfor purposes to be described presently. To permit the required movementof the rod and sleeve member longitudinally of the tool spindle i4, thesleeve is slidably received in a counter bore 54 in the upper end of thespindle as shown in Fig. 1. A coiled compression spring 55 interposedbetween the bottom of the counter bore and the lower end of the sleeveurges the adjusting rod upwardly or toward the tool contractingposition.

With the arrangement above described the tool adjusting rod is shiftedtoward the tool expanding position by an endwise movement of theactuating member 42 downwardly as viewedk in Fig. 1. However, due to thepresence of the spring 48, the actuating member may continue its advancewhile the adjusting rod remains stationary in the event that theresistance offered to further expansion of the tool exceeds apredetermined value. This prevents the application of excessive pressureto the honing tool and efy fectually guards against damage to the toolor work when unexpected resistance to tool expansion is encountered.

Endwise tool expanding movements may be imparted to the actuating member42 by either of the pressure iiuid actuators 40 or 4I'. The actuator4I), in this instance, is arranged to effeet a continuous rapid advanceof the member to initially expand the tool into operative engagementwith the work. To this end, the member 42 is provided at its upper'endwith a pistonmember working in a cylinder 6I rigidly supported in theupper end of the tool head I2 con centric with the spindle I4. Pressure:duid may be introduced into the cylinder above the piston through apipe 62 thus forcing the piston and associated parts downwardly ortoward the tool expanding position. The piston, in this instance, isloosely mounted on the member and is formed with a sleeve-like extension63 having at its outer end an internal iiange 64 adapted to bear againstthe upper end of the member 42 and thus effect a one-Way drivingconnection with the member. This extension projects through acap 65whichcloses the upper vend of the cylinder and is threaded for the.reciprocation of a nut 66 adapted to act as an adjustable stop toylimit the vextent of movement of the pis# ton-toward the open end ofthe cylinder. A lock nut 66 threaded on lthe sleeve cooperates with the-nut .66 vto retain the latter iin adjusted position.

vThe actuator 4| is arranged to advance the actuating ember 4 2 insuccessive steps to .effect a positive stepped expansion of the honingtool. For this purpose, the actuator is operated intermittently underthe control of any suitable means, .as for example a timer, ashereinafter set forth, and the actuating member 4 2 is rotatedintermittently Aabout its longitudinal axis while a stationary nut 10engages a lead screw 'il rigid with the member. As shown 'in Figs. 1 and2 the actuator 41| in its preferred `form comprises a piston 12 workingin a cylinder 13 mounted in a `horizontal position on one side of thetool head I2. The piston is provided :With a piston rodfM extending intothe head and having racl; teeth 1.5 (Fig. k2) meshing with a Vpinion 16rotatably supported'between spaced collars 11 xed to :the

actuating member 42. The teeth of the pinion are `sufficiently wide toretain their meshing engagement with the rack teeth as the pinion movesaxially with the member between tool expanding and ,contractingpositions. o f the pinion 1 6 `are transmitted to the actuating memberthrough a one-way driving con.-

nection of -any suitable type interposed between the pinion `and themember. As herein shown, this `connection comprises a ball type clutch18 arranged to drive ,the actuating member when the pinion 16 is rotatedin a clockwise direction as-viewed 1in Fig. 2. When the pinion isrotated in the opposite direction, the driving connection is interrupted.thus ,allowing the actuator to return to its normal rest position whilethe actuating member is retained in the rposition to which it --waspreviously operated.

In the particular machine illustrated rotation ofthe pinion in thedirection to drive the Aactuating member is effected by introducingpressure fluid into the outer end of the cylinder 13 through a pipe 19thereby shifting the piston and its rod toward ythe right as Viewed inthe drawings. An adjustable stop screw 8U positioned for engagement bythe inner end of the piston'rod determines the length of the pistonstroke and thus the angle through which the actuating member is rotatedin each operating cycle of the actuator. When `the pressure on thepiston 12 is relieved by the action of the control mechanism in shift-111g theconnection of the pipe 19 from the pressure fluid source to thedrain, a spring 8l returns the piston to its normal rest position at theouter .end of the cylinder. Ordinarily, no rotation ,is imparted to theactuating member in .this return lmovement due to the release of ,theclutch 18. j

The lead screw and nut mechanism b y which the rotating movements ci thevactuating member are `translated into intermittent vendwise steps isshown in Figs. l and 3 of the drawings. In the exemplary machine thelead screw 1I is formed by threading an enlarged section 82 of theactuating member. AThe nut 1 0 in its preferred form comprises agenerally vrectangular block having an arcuate recess in one facethreaded for engagement with the screw threads 1I. Thus the nut may bemoved 4into .or out of engagement with the lead screw as required.

Relative movements til' With the nut -i-n the .engaged position,positivel longitudinal movement in .steps of 'predetermined length willbe imparted .to the actuating member as the member is intermittentlyrotated by the actuator M. v4When the nut is disengaged, vthe actuatingmember may V.be shifted rapidly to tool expanding position by theactuator 40 or returned to tool contracting position under the influenceof the spring 55.

While any suitable means may be employed for shifting the -nut 'l0between engaged and disengaged positions, it is preferred to utilizepressure uid operated means for this purpose because of the ease withwhich the operation of the nut may be synchronized with the variousoperations of the machine. 'The pressure uid operated means as hereinshown .comprise a piston 83 (Figs. 1 and 4) working in `a cylinder 84.The cylinder is rigidly supported on the frame work of the spindle 'headI2 as shown in Figs. 1 and 3 with its axis disposedin a horizontalposition and substantially alincd with the axis of the actuating member42. At its inner end the cylinder is formed `with recess 85 of generallyrectangular cross-section dimensioned to receive the nut 10 with avsliding fit. A piston rod 86 extends from the piston to the nut and isdrivingly connected therewith as by a pin 81 which permits a limitedvertical movement between the parts to eliminate any binding due Itonon-engagement of the lead screw and the nut. A spring 88 interposedbetween the piston and the inner end of the cylinder normally urges thepiston to the right as viewed in Figs. 1 and 3 and thus tends tomaintain the nut 10 in the disengaged position, Pressure uid introducedinto the outer end of the cylinder 84 through a pipe 89 shifts thepiston to the lef-t against the influence of the lspring 88 and thusmoves the nut `into engaging relation with the lead rscrew thread 1I.

The operations of the hone expanding actuators 4Q and 4| are coordinatedfor most e'icient operation by timing the action of thenut actuatingmechanism in ac cordance Vwith the operation of the actuator 40 toeffect initial rapid vexpansion. More particularly the nut is maintainedin its disengaged position to avoid interference with the operation ofthe actuator 40 until the piston Si! reaches the end of its operatingstroke as determined by the setting of the stop nut 66. The nut 10 isthen automatically shifted into engagement with the lead screw threadsand the actuator 4I thus becomes effective to continue the advance ofthe actuator in intermittent steps and thereby expand the hone insuccessive positive steps.

Automatic control of the nut actuating mechanism is effected 4in theexemplary machine by connecting the cylinder 8 4 and the actuatorcylinder 6l in parallel through a sequence or foot valve SV (Fig. 4).This valve may be of the conventional type arranged to open and allowpressure fluid to ypass into the pipe 89 only when the fluid in the pipe5,2 reaches the pressure for which the valve is adjusted. Thus thedelivery of pressure uid to the cylinder 84 is conditioned upon thebuilding up of a predetermined pressure in the actuator cylinder and maybe accurat-ely timed to take place `at the exact instant necessary formost eicient operation of the honing tool. The sequence valve, ofcourse, is arranged to permit unrestricted fluid ow in the reversedirection when the pressure in the pipe .52 is relieved. The fluid maytherefore be eX- hausted from the cylinder 84 by the action of the'spring 88 upon rthe piston 83. r The automatic control'of the honeexpanding mechanism leliminates the need for close supervision of themachine lduring its operating cycle and'moreover insures'operation ofthe honing vtool in the most eilicient manner. Through the medium ofthese controls and others shown in Fig. 4, the machine attendant isrelieved of substantially all duties except that 4of loading the workfonthe workvsupport and removing the iinished work therefrom after themachine has been set up for a particular job.- Thus an operating cycleof the machine is started by momentarily closing a starting switch S'-(Fig. 4) to energize a-pair of motor control relays RI and R2. Relay RIcloses switch RH toL start the spindle driving motor M. Relay R2closes'switch R2I to start the pump motor' Mi. As the pump P begins tofunction, pressure iluid is supplied through the reversing valve" RV tothe upper end of the -head reciprocating cylinder 26 thus moving thetool head down-'- wardly and entering the tool in the work. Theattendant may release the starting switch Sas soon as the tool headleaves its normal rest' position which results in the closure of a limitswitch LSI in well knownmanner. The limit switch completes a holdingcircuit for the relays RI and R2 which circuit includes a switch RIZ,closed by the relay RI when energized, and normally closed manuallyoperable switches Sl and S2. Switch Sl is the inching switch commonlyused in honing machines. Switch S2 is the fstop switch by which theoperation of the machine may be yinterrupted at any point in its cycle.

When the tool head advances suiiiciently to enter the tool in the work,a suitable cam engaging member carried by the head engages a cam 9| on avertical rock shaft 92 and through a linkage 93 closes a limit switchLS2. .Closure of this limit switch energizes a control relay R3 which,in turn, closes a switch R3! to energize a solenoid SOL. l. Thissolenoid is operatively associated with the valve V3 and is arrangedwhen energized to set the valve in a position to connectV the dischargeline from the pump PI to the actuator 1li] and to the nut actuatingcylinder 84. In its alternate position the valve V2 connects theactuator and the cylinder to.

^ the drain 28. Upon connection of the pump Pl concurrentiywith theactuation of the's'tarting switch S to energize the motor relays RI andR2, a runningcircuit is completed for a motor driven timer TM and` for amotor driven Acurrent interrupter CI. The timer, in well known manner,determines the length of the opera-ting cycle of the machine and actsto-stcp the saine at the end of the cycle as will be explainedpresently. The interrupter intermittently closes and opens a, switch S3to energize and deenergize a control relay R4. The relay through itsswitch RM controls the circuit for a Asolenoid SOL. 2 associated withthe valve V2 whereby the valve alternately connects the actuatorcylinder 13 to the pump PI and'to the drain 28. The piston.12 isaccordingly reciprocatedfwithin the cylinder and, through the pinion 'I3and the clutch 1B, imparts successive rotative steps to the toolactuating member 42- When the nut is shifted into engagement with thelead screw threads as above explained,` the actuating member and the'tool `expanding rod 31 are advanced step by step to `progressivelyexpand the honing tool. i

Reciprocation of the head l2 through a succession of strokes eiective totraverse the honing tool repeatedly from one end of the work piece tothe other continues under control of the reversing valve RV and theassociated pilot valve PV in the usual and well known manner. After apredetermined operating interval as determined by the timer TM, thelatter closes its switch S4 to eiect the energization of a control relayR5. The relay by closing switch R51 energizes a pull-v out solenoid PSwhich, through a suitable me# chanical linkage, rocks the control rod.29 to a position in which the intermediate stop 32 isY ineffective forcontrol purposes. The tool head is thus free to move beyond an upperlimit of the working stroke to the Withdrawn or normal rest position.

As the head passes the upper limit of the working stroke, the camengaging member on the head engages a cam 94 on the control rod 9| androcks the rod into a position to open the limit switch LS2. Thisinterrupts the circuit for the control relay R3 which, in turn,interrupts the circuit for the solenoid SOL. l. Valve V3 is thereuponreturned to open position in which it connects the actuator cylinder 6|and the nut actuating cylinder 84 with the drain 28. The pistonsoperating in these cylinders are immediately returned to their normalrest positions by their associated springs. Disengagement of the nut 'Hlfrom the lead screw threads as a result ofthe return of the piston 83permits rapid return of the actuating member 4,2 and tool expanding rod31 with corresponding rapid contraction ofthe hone tool. The tool maytherefore be withdrawn from the work without danger of injury to eitherthe tool or work.

The tool head l2 upon reaching its normal rest position acts through themember 33 and upper limit stop 3l to condition the pilot valve PV forthe next operating cycle,that is, it sets the valve in the positionshown in Fig. 4. At the sami. instant the limit switch LSI is opened tointerrupt the holding circuit for the relays RI and R2. The relays andtheir associated solenoids accorde ingly become `deenergized and stopthe machine. Operation of the interrupter CI and timer TM is alsoterminated, the latter being reset automatically in well known mannerfor the next operat ing cycle. Thus the head is stopped with the toolwithdrawn from the work so that the attendant may remove the finishedworkpiece from the machine and replace it with the next workpiece to beoperatedon. l y

It will be apparent from the foregoing that the invention provides novelpower actuated means for expanding a honing tool in a manner effectiveto attain the most eiicient results. The iinproved mechanism operates toeffect a rapid initial expansion of the honing tool to operativelyassociate the abrasive elements thereof with the work and thereafter toeffecta positive and progressive stepped expansion of the tool while theabrasive elements are operating on the work.

Due to the rapid initial expansion of the tool, the non-working portionof the machine cycle is` reduced to a minimum. Moreover the improvedtool actuating mechanism provides for rapid contraction of the tool atthe end ofy the. working cycle thus further reducing non-productivetime.

`The invention also provides a novel safety mechanism which effectuallyprevents the application of excessive pressure to the honing tool andthereby guardsv against. damage to the tool or work under abnormaloperating conditions.

We claim as our invention:`

1. A honing machine having, in combination, a support fory an expansibleand contractible honing tool, a support for work to be operated on bythe tool, means for effecting relative rotation and simultaneousrelative reciprocationl of the tool and work supports, a rst toolactuating means operable to effect a rapid initial expansion of the toolinto operative engagement with the work, a second tool actuating meansoperable to effect positive expansion of the tool in intermittent stepsvwhile the tool is operating on thework, and control means operative togovern the operation of said tool actuating means selectively.

2. A honing machine having, in combination, a support for an expansibleand contractible honing tool, a support for work to be operated on bythe tool, means for eiecting relative rotation and simultaneousrelativey reciprocation of the tool and work supports, power actuatedmeans operable to eiiect a rapid initial expansion of the tool intooperative engagement with the work, other power actuated means operableto effect expansion of the tool in intermittent steps, and control meansoperative automatically to initiate the. operation of said other poweractuated means upon the completion of the operation cf said firstmentioned power actuated means.

l3. A. honing machine having, in combination, a` supportv for anexpansible and contractible honing tool, a support for work to beoperated on by the. tool, means for effecting relative rotation andsimultaneous relative reciprocation of theA tool and work supports, apair of independently operable power actuated mechanisms each operativeto expand the hone, control means operative to initiate ther operationof one of said mechanisms, and other control means actuated in responseto a predetermined expansionV of the tool by said one mechanism toinitiate the operation of the other of said mechanisms.

4. A honing machine having, in combination, a support for an expansibleand contractible honing tool, a support for work to be operated on bythe tool, means for effecting relative,` rotation and simultaneousrelative; reciprocation of the tool and work supports, power actuatedmechanism operable to eiect rapid continuous expansion of the tool,other power actuated mechanism operable to eiect positive expansion ofthe tool in intermittent steps, control means operative to initiate theoperation of 'said other mechanism upon engagement of the work by thetool, and timing means operative to determine the rate of expansion ofthe tool by said other mechanism while the tool is operating on thework.

5. The combination with a honing tool, of an elongated actuating membershiftable longitudinally to expand and contract the tool, a first powerdriven actuator acting directly on said member to shift the member totool expanding position, and a second power driven actuator arranged torotate said member about its longitudinal axis,- said member having athreaded portion engageable with a stationary nut operative to impartlongitudinal movement to the member in response to its rotation by saidsecond actuator.

6. The combination with an expansible and contractible honing tool, ofan elongated actuating member shiftable longitudinally to expand andcontract the tool, screw threads formed on a section of said member, apower driven actuator directly coupled with said member and operable toshift the member in a direction to expand or contract the tool, a secondpower driven actuator operable to rotate said member in intermittentsteps, and a threaded nut shiftable into engagement with the threadedsection of. said member in timed relation to the operation of said rstmentioned actuator, said nut acting to` shift said member in a directioneffective to expand the tool incident to the rotation of the member.

7. The combination with an expansible and contractible honing tool, ofan elongated actuating member shiftable longitudinally to expand andcontract the tool, screw threads formed on a section of said member, apower driven actuator directly coupled with said member and operable toshift the member in a direction to expand the tool, a second powerdriven actuator operable to rotate said member, a threaded nut supportedfor movement only transversely of said member into and out of engagementwith the threaded section of the member, and power actuated meansoperating in timed relation to the operation of the first mentionedactuator for moving said nut into and out of engagement with thethreaded sections of said member, said nut when engaged acting to shiftsaid, member in a direction to expand the tool incident to the rotationof the member.

8. Thel combination with an expansible and contractible honing tool,l ofan elongated actuator member shiftable longitudinally to expand andcontract the tool, screw threads formed on said member, a pressure fluidactuator directly coupled with said member operable to shift the memberin a direction to expand the. tool, power actuated means operable torotate said member, a threaded nut supported for movement onlytransversely of said member into and out of engagement with the screwthreads thereon and operative when engaged to shift the memberlongitudinally incident. to the rotation of the member, a pressure uidactuator operable to shift said nut between engaged and disengagedpositions and a circuit arranged to supply pressure fluid to saidactuators in predetermined sequence.

9. The combination with a honing tool, of an elongated actuating membershiftable longitudinally to expand and contract the tool, screw threadsformed on said` member, a nut supported for movement only transverselyof said member into or out of engagement with said screw threads, powerdriven means operable to rotate said member, said nut when engaged withthe screw threads acting to impart longitudinal movement to the memberin response to such rotation, and a power driven actuator coupled withsaid member operable to shift the member longitudinally when said nut isdisengaged from the screw threads, said actuator having a one-wayconnection with the member to permit independent movement of the memberin one direction.

l0. The combination with a honing tool having an axially movableadjusting rod associated therewith, an elongated tubular membersupported substantially in axial alinement with the tool and to impartthereto the movements of the member, spring means interposed betweensaid elements eiective to permit `limited relative movement between saidother element and the member when the resistance of the adjusting rod tomovement reaches a predetermined value, and means for adjusting theposition of said one element with reference to said member to regulateAthe tension of said spring means.

11. The combination with a longitudinally shiftable tool adjustingmember having a threaded section, `of a iirst pressure uid operatedactuator coupled directly with the member andopervative to impart rapidlongitudinal movement "thereto, means for imparting slower longitudinal-movement to the member in' successive positive steps including asecond'pressure uid operated actuator operative to rotatethe member inintermittent steps, a nut supported for movement transversely of thethreaded section of the member between disengaged and thread engagingpositions, means normally eifective to hold said nut in the disengagedposition, and means for shifting said nut to the engaged positionintimed relation to the operation of said rst actuator.

12. The combination with a longitudinally shiftable tool adjustingmember having a threaded section, of a rst pressure fluid operatedactuator coupled directly with the member and operative vto impart rapidlongitudinal movement thereto, means for imparting slower longitudinalmovement to the member in successive positive steps including a rsecondpressure fluid operated actuator operative to rotate the member inintermittent steps, a vnut supported for movement transversely of thethreaded section of the meinb'er between disengaged and thread engagingpositions, means normally eifective to hold said nut in the disengagedposition, pressure iiuid operated means connected in parallel with saidfirst actuator operative to shift said nut into the engaged position,and a control valve for timing the operation of said nut shifting meanswith respect tothe operation of said first actuator.

13. The combination with a longitudinally shiftable tool adjustingmember having a, threaded section, ofa rst power actuated meansoperative to impart relatively rapid continuous longitudinal movement tothe member, means for imparting slower longitudinal movement Ito themember'in progressive stepsincluding a second power actuated meansoperative to rotate the member about its longitudinal axis inintermittent steps, a nut movable transversely of the threaded sectionof the member into or out of engagement with the threads thereof, meansnormally effective to hold said nut in a disengaged position, and athird power actuated means operative to move said nut into engagedposition to render said second power actuated means effective. e

14. The combination with a longitudinally shiftable tool adjustingmember having a threaded section, of a first power actuated meansoperative to impart `relatively rapid continuous longitudinal movementto the member, means for imparting slower longitudinal-movement to themember in progressive steps including a second power actuated meansoperative to rotate the member about its longitudinal axis inintermittent steps, a nut movable transversely of the threaded sectionof the member into or out of engagement with the threads thereof, meansnormally effective to hold said nut in a disengaged position, meansoperable to shift said nut into engaged position and thereby render saidsecond power actuated means effective to impart longitudinal movement tothe member, and control means for initiating the operation of said nutshifting means in timed relation to the operation of said first poweractuated means.

15. The combination with a rotatable honing tool having a plurality ofradially movable abrasive elements, of an adjusting mechanism includinga member shiftable axially of the tool to impart said radial movementsto the abrasive elements, power actuated means operable to shift saidmember at arapid rate, other power actuated means operable to shift saidmember at a vslower rate, and control means eiective to initiate theoperation of said otherpower actuated means in response to apredetermined increase in the resistance offered by said member tomovement by said rst power actuated means.

16. A honing machine having, in combination, a support for an expansibleand contractible honing tool, a support for work to be operated on bythe tool, means for effecting relative rotation and simultaneousrelative reciprocation of the tool and work supports, pressure fluidactuated means operable to eiect a rapid expansion of the tool intoengagement with the work, other pressurefluid actuated means operable toexpand the tool at a slower rate while operating on the work, and valvemeans operative to initiate the operation of said other pressure uidactuated means when expansion of the tool byv the first `mentionedpressure iiuid actuated means is interrupted by the initial engagementof the tool with the work.

17. A honingmachine having, in combination, a support for an expansibleand contractible honing tool, a support for work to be operated von bythe tool, means for effecting relative rota-

